Grinding and drying, gypsum calcination

The perfect dedusting solutions to fulfil the strictest of requirements

Whether the process involves grinding, drying or calcination, the aim in every case is to eliminate water from the raw material. In state-of-the-art technology, this is accomplished using an all-in-one unit. At the end of the grinding product calcination process, the exhaust air that is produced is extracted and separated in a filter.

The moisture lands in the filter, whose design has to be able to ensure that the filter medium has a sufficiently long service life. Scheuch specialises in this area and boasts years of expertise in using extraction systems in the plaster industry.

The following requirements must be considered:

Various fuels (light or heavy oil, gas, etc.)

Recycling material, FGD gypsum and natural gypsum with some impurities (glass fibres, cardboard, paper, etc.) land in the filter

EMC TECHNOLOGY

Energy Minimizing Concept

EMC filter technology from Scheuch has revolutionised dedusting in the cement industry and set new standards in bag length, pressure loss, cleaning pressure and bag service life. The results point to a clear reduction in life cycle costs (LCC). Thanks to its patented status, EMC is unique and is deemed to be the Best Available Technology (BAT) for process filters – even when compared with electrostatic and reverse-air filters. More than 200 EMC filter plants installed within the first ten years of this technology outline its pre-eminent status worldwide.

Design features

Volume flow rate up to 3,000,000 Bm³/h

Filter area up to 40,000 m²

Bag length as much as 12 m and beyond

Dust quantity over 1,000 g/m³

Hot gas design up to 280 °C

IMPULS filters

IMPULS FILTERS

Outstanding cleaning performance combined with an excellent degree of separation

The Scheuch IMPULS filter is a high-capacity filtering separator that delivers outstanding cleaning performance combined with an excellent degree of separation. It is used for the dry separation of solid matter, primarily in the extraction of contaminants from machinery and the workplace, as a process filter in material recycling, or for conveyed material separation purposes.

The patented IMPULS cleaning system

Thanks to the specially shaped twin nozzles on the jet pipe, the pulsed free jet pulls along an envelope of clean gas from the primary compressed air as it makes its way to the injector. The two gas flows are mixed in the injector by means of pulse exchange and, at the same time, experience a significant increase in pressure. This ensures highly efficient cleaning throughout the bag length and filter bags that require cleaning less frequently.

Proven in practice for decades, the IMPULS cleaning system has become a byword for low operating costs:

Low compressed air consumption

Long service life demonstrated by filter media

Very little maintenance or servicing required

Radial fans

RADIAL FANS VS

The right plant concept for the perfect fan specification

A plant's ability to demonstrate a high level of safety and reliability is essentially dictated by its key components. The radial fan is one of the components at the heart of every extraction, dedusting, exhaust and flue gas purification, and pneumatic conveying plant. It helps to meet customer requirements with a level of quality that guarantees fault-free operation and excellent performance between maintenance intervals.

There are three different drive types available:

Drive direct via motor shaft

Drive via belt

Drive via coupling up to 1,000 kW

There are also three different types of impeller:

Impeller for transporting clean gases

Impeller for transporting gases and shavings with high dust concentrations

Impeller for transporting fibrous material

Material transport/Conveying mechanisms

MATERIAL TRANSPORT/CONVEYING MECHANISMS

Reliable and safe

When it comes to ensuring availability and operational safety in dedusting plants, conveying mechanisms are just as crucial as fans and filter systems.

All conveying mechanisms can also be used in explosive, dust-laden atmospheres as defined in Directive 94/9/EC (ATEX).

Mechanical conveying

In the cement industry, rotary valves are used as continuous discharge or dosage devices with slight negative pressure/overpressure for air exclusion purposes. The advantages of rotary valves lie in their comparatively low construction size combined with a high, speed-dependent conveying output, their ability to be used in a wide range of temperatures and with various pressure differences, and the relatively low energy costs associated with them.

Tube-type and trough screws are used to continuously transport bulk materials, at throughput volumes of 2 to 500 m³/h and with screw diameters between 200 and 1000 mm.

Pneumatic conveying – High-pressure conveying systems

The longer the material conveying path and the higher the quantity of material that needs to be transported, the more sensible a choice high-pressure systems become. The main components of these are a high-efficiency rotary blower plus a rotary valve and an injector. Together, they ensure efficient conveying even when dealing with significant material quantities. High-pressure systems are ideal for use with conveying quantities of 1 to 100 t/h, conveying systems of up to 1500 m in length, and nominal widths between 88 and 500 mm.

Material loading stations

Material loading stations consist of a rotary valve with an injector directly attached to it. The rotary valve loads the material into the pneumatic conveying system in a controlled manner. If it needs to handle items that cause wear, the system can also be lined with special materials.

Electrostatic precipitator conversion

ELECTROSTATIC PRECIPITATOR CONVERSION

Bag filters: State-of-the-art filters for kiln

Some years ago, virtually all kiln and clinker cooler filters – as well as some cement mill filters – were the electrostatic precipitator (ESP) type. As these have become unable to live up to growing requirements relating to emission limit values as well as operational safety and availability, however, electrostatic precipitators across the world are steadily being converted into bag filters. Compared with electrostatic precipitators, these ensure significantly lower clean gas dust loads and a consistent degree of separation.

The result is that almost every customer today plumps for the bag filter variety when installing new kiln filters.

Electrostatic precipitator housings are generally very tall in comparison to bag filters, making them ideal for conversion to EMC filters with bags which, over time, have grown to as much as 12 m in length. Excellent use can be made of the available space without the need to extend the housing – saving costs and cutting down on assembly time as conversion can usually be carried out during a scheduled inspection.

Thanks to Scheuch's comprehensive modular system comprising a range of filter head widths and bag lengths, it is possible to find exactly the right module for any housing dimension and thus maintain the required filter area. During the process of planning the engineering work for the conversion, a CFD flow analysis is performed where necessary in order to ensure a uniform inflow for all filter bags.

Fresh air cooling

FRESH AIR COOLING

Cooling exhaust gas using fresh air

As an alternative to an gas conditioning tower, gas can also be cooled using a system that injects fresh air. This design is equipped with a mixing chamber where the fresh air is blown in and added to the process gas. The fresh air mixes with the hot exhaust gas, thus reducing its temperature. Compared with gas conditioning towers, this solution incurs lower construction costs; however, since it also involves a higher volume flow, the filter plant must have larger dimensions.

We provide systems for maintaining clean air

Innovative air and environmental technology for industrial applications has been Scheuch‘s stock in trade for 50 years now. Whether the solutions involve extraction, dedusting, conveying, flue gas purification or plant manufacturing, Scheuch is a leading expert with a pole position on the market in numerous sectors, and offers its customers application-specific, high-quality solutions to their air and environmental technology issues.